On an M1 rifle the serial number was only applied to the receiver. What might be referred to as part numbers were applied to some of the larger parts (receiver, barrel, bolt, hammer, trigger housing, operating rod, gas cylinder) that usually consisted of a letter (C or D) representing a drawing size, a number representing the drawing number, and the manufacturer's identification (SA - Springfield Armory, WRA - Winchester Repeating Arms and etc.). A dash followed by a number indicted the revision number to the drawing. Obviously the lower the revision number the earlier the part was manufactured.
With these revision numbers modern C&R collectors have gone a little berserk to exchange parts, that were replaced, with parts that are "correct" for their rifle. This generated by the johnny-come-lately C&R writers that have published this information.
Since the military history of this piece stopped apparently sometime during WWII it can be expected that most, if not all, of the parts are original to it and the drawing revision numbers on the parts are "correct." If no parts were replaced on the rifle, which may be indicated by the drawing revision numbers, then it can be a statistically useful piece to further document the general time period these parts were assembled to rifles. BTW these revision numbers will not all be the same, as revisions to the drawings were made independently and at different times.